Mickelson began working with Harmon in the spring of 2007 and captured 12 PGA Tour titles, including the 2010 Masters and 2013 Open Championship, during the past eight years. Mickelson has fallen to No. 25 in the world and only has five top-10 finishes since his victory at Muirfield.

In a statement released to Golf.com, Mickelson said: “I’ve learned a great deal from him in our eight years together. It’s just that at the moment I need to hear new ideas from a different perspective.”

In a separate statement, Harmon told Golf.com that he “thoroughly enjoyed” working with Mickelson and he sees “nothing wrong” with the 45-year-old seeking help elsewhere.